def city(city,country,population=''):
	'''输出城市和国家'''
	if population:
		ss = city.title() + ' ' + country.title() + '-' +population.title()
	else:
		ss = city.title() + ' ' + country.title() 
	return ss
	
first_city = city('santigo','chile')
print(first_city)

soccer_city = city('santigo','chile','a:1000')
print(soccer_city)
